How the mill works

Dust Floor (fourth floor)

The dust floor is at the top of the mill on the fourth floor. Sitting directly beneath the cap this floor helps to prevent dust and dirt from falling on the mill floors below. This floor is also the powerhouse, or engine room, of the mill.

The windshaft is the large horizontal shaft that is turned by the sails. It is attached to the brake wheel – the first gear wheel in the mechanism for transferring the energy from the wind to the millstones two floors below. The brake wheel turned the wallower (see photo, right) and main spindle. The sails move anti-clockwise and the stones would have turned clockwise.

At Brixton Windmill the brake wheel has been disengaged from the wallower because the millwright was uncertain about the provenance of the machinery and whether the building would be able to withstand the strain put upon it when the sails turned and moved the mechanism.

Bin Floor (third floor)

The bin floor, as the name suggests, is the floor where the sacks of grain (wheat, barley and oats) would have been stored before milling. Today, we store grain on this floor and use it for demonstrations. Throughout the mill there are trap doors for the sack hoist – a very clever mechanism that would have used wind power to pull the sacks of grain from the ground flour.

Image: Owen Llewellyn

Stone Floor (second floor)

The stone floor is where the wheat would have been ground. This floor is dominated by the spur wheel – one of the last gears in the windmill’s mechanism.

The millstones are encased in a wooden vat (see photo, right). Originally a spout would have led from the bin floor above to the hopper (a wooden container that feeds the grain to the stones below). The spout would have supplied the stones with a constant supply of grist – another name for grain – to the stones.

The grain was fed into the centre of the stones and was thrown to the outer edge by centrifugal force. As it moved it was ground into flour by the grooves on the inside faces of both stones. A paddle set on the outer edge of the top stone collected the flour and swept it into a hole in the floor.

At Brixton Windmill the stones are made of Derbyshire grit. The top stone is the one that moved and is called the runner stone. The bottom stone remained stationary and is called the bed stone.

There are also wooden bins on this floor.

Meal Floor (first floor)

Traditionally, the meal floor is where the meal (the name for grindings of any grain) would have been collected. The wheat flour ground by the stones would have travelled down a spout to this floor to be collected in a sack. If you look up you can see the bed stone – the bottom of the millstone. You can also see the centrifugal governor made of cast iron which would have controlled the distance between the stones and kept the millstones at a constant speed as the speed of the wind changed.